You can't with the image dimensions and styling that you are using.
By default we use background-size: cover which means that the image will fill the available area and be clipped, and that's what you are seeing.
If you don't (or use other another background-size value such as "contain"), then the image will be displayed within the area and not be clipped, so you see a letterbox effect (bars on the sides, or with different dimensions potentially on the top/bottom). You can change the background color, but you can't change the effect.
Long story short, if you want to use two subscriptions and have the "cover" effect, you should adjust your images to better match the display dimensions.